<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <select name="province">
        <option value="1">河南</option>
        <option value="2">江苏</option>
        <option value="3">山西</option>
        <option value="4">吉林</option>
        <option value="5">浙江</option>
    </select>

    <select name="city">
        <option value="1-1">郑州</option>
        <option value="1-2">开封</option>
        <option value="1-3">洛阳</option>
        <option value="1-4">商丘</option>
    </select>
    <hr>

    <select name="">
        <optgroup label="河南">
            <option value="1-1">郑州</option>
            <option value="1-2">开封</option>
            <option value="1-3">洛阳</option>
            <option value="1-4">商丘</option>
        </optgroup>

        <optgroup label="江苏">
            <option value="1-1">南京</option>
            <option value="1-2">苏州</option>
            <option value="1-3">无锡</option>
            <option value="1-4">常州</option>
        </optgroup>
    </select>
</body>
</html>